Birch Shieldbug
Elasmostethus interstinctus

The Birch Shieldbug is found across the northern hemisphere, including the UK. As its name indicates, it is usually associated with birch trees.
The adult is green with wide chestnut brown borders to its "scutellum" (triangular shield), including the lower part and brown on its wing membranes. The underside is green.

The Birch Shieldbug is much smaller than the similar-coloured
Hawthorn Shieldbug (two together above right) and has some brown on its scutellum, unlike the Hawthorn and the Juniper Shieldbug, another look-alike with lighter brown borders to only the sides of the scutellum and wing case.